Railroad refrigerant compressor drive



Sept. 19, 1939. c. R. NEESON El AL RAILROAD REFRIGERANT COMPRESSOR DRIVE 8 Sheets-Sheet 1 Filed Dec.

INVENTOR N Y ON mm M M M R T 5 #7 .A mm a R i Y B c. R. NEESON ET AL RAILROAD REFRIGERANT COMPRESSOR DRIVE 8 Sheets-Sheet 2 Filed Dec. 2, 1937 CHARLES RNEESON FRANK B. CONLON ATTORNEY.

P 1939- c. R NEESON ET AL 2,173,285

RAILROAD REFRIGERANT COMPRESSOR DRIVE Filed Dec. 2, 1957 8 Sheets-$heet 3 INVENTOR. CHARLES RJ'JEESON F'RANK BCONLON J M 72% kw ATTORNEY.

p 1939- c. R. NEESON ET AL 2,173,285

RAILROAD REFRIGERANT COMPRESSOR DRIVE Filed Dec. 2, 1957 8 Sheets-Sheet 4 IO P INVEN TOR CHARLES RJVEESOA/ FRANK a. COIy/LOIQ/ ATTORNEY Sept. 19, 1939. c. R. NEESON ET AL RAILROAD REFRIGERANT COMPRESSOR DRIVE Filed Dec. 2, 1937 8 Sheets-Sheet 5 INVENTOR. CHARLES R.NCE'5ON BY FRANK 5. cu LON M A; fizz kzawiu ATTORNEY.

Sept. 19, 1939. NE QN Er AL 2,173,285

RAILROAD REFRIGERANT COMPRESSOR DRIVE Filed Dec. 2, 1937 8 Sheets-Sheet 6 INVENTOR. CHARLES Manson FRANK a. CONLON BY E; L7H; 9f;

ATTORNEY.

Sept. 19, 1939. c. R. NEESON El AL 2,173,285

RAILROAD REFRIGERANT COIPRESSOR DRIVE Filed Dec. 2, 1957 I a Sheets-Sheet 8 ATWRNEY Patented Sept. 19, 1939 UNITED STATES RAILROAD REFRIGERANT COMPRESSOR DRIVE- Charles B. Neeson and Frank B. Conlon, Dayton,

Ohio, assignors,

by mesne assignments, to

Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application December 2,1937, Serial No. 177,895

15 Claims.

The subject of our invention is the provision of means for driving a compressor located on a vehicle such as a railroad car, particularly for use in compressing a refrigerant. Although the invention is particularly designed for air conditioning passenger cars it is within the purview of our invention to refrigerate commodities in refrigerator cars, or to air condition other vehicles or stationary enclosures, or to refrigerate commodities therein, by the use of part or all of the present invention. Accordingly the term refrigeration may be used herein to denote any or all of the aforementioned functions.

The principal object of the present invention is to devise a refrigerating system capable of delivering maximum refrigeration at low car speeds and also capable of delivering the same amount of refrigeration at very high car speeds without, however, attempting to control the speed of rotation of the compressor crank shaft. Several types of compressor drives are at present on the market which derive energy from the motion of the car and which include means to translate the variable speed of the car axle into a constant speed for the compressor crank shaft, which constant speed is equal to the speed at which the compressor is operated by a motor for stand by service. Such systems require expensive and in many respects delicate mechanisms which need constant servicing and often fail. With our invention the car speed and, hence, the axle speed from which mechanical energy is obtained is directly translated to the speed of the compressor crank shaft, the control of refrigeration being achieved by utilizing a compressor such as set forth in the co-pending application of Charles R. Neeson, Serial No. 177,694 filed concurrently herewith, wherein a function of the load on the compressor is caused to control the number of cylinders of the compressor which are permitted to compress refrigerant. In applying the compressor of the aforesaid application to the present invention, it is obvious that the load is a variable factor which affects the number of cylinders in operation, but the speed is a far greater variable factor which also affects the number of cylinders in operation. If the load remains constant the cubic feet per minute of vaporized refrigerant exhausted from the compressor will rise in substantially direct proportion to an increase in speed of the car axle, which results in greater rariflcation and decreased pressure within the crank case causing operation of means responsive to the pressure within the crank case to reduce the number of cylinders permitted to operate. Other cylinders will continue to exhaust refrigerant from the interior of the crank case until such time as a variation in the load or the speed of the car axle causes an increase or decrease in the number of cylinders inoperation.

It is a feature of our invention that many details of railroad air conditioning systems have been eliminated or extremely simplified, an object of the present invention being to devise a system having relatively few operating parts, all of which are extremely rugged, easy to assemble and disassemble for inspection and repair, and unlikely to fail in service. The advantages of our invention will be fully apparent following an inspection of the specification and accompanying drawings wherein like numerals refer to like parts throughout.

In the drawings Fig. 1 is a schematic representation of a railway vehicle having our present invention applied thereto; Fig. 2 is a bottom view of the vehicle shown in Fig. 1; Fig. 3 is a cross section through the body of the vehicle taken along line 3-3 of Fig. 2, showing a form of air conditioning unit and duct system and the manner of air distribution thereof which may be found desirable in certain types of cars; Fig, 4 is a plan view of the end of a vehicle having the foregoing air conditioning unit and ducts applied thereto, the roof and half-decks of the vehicle being removed for the sake of simplicity; Fig. 5 is a schematic representation of the driving mechanism and the compressor as applied to a car body; Fig. 6 is an end elevation of apparatus such as shown in Fig. 5; Fig. 7 is a cross section through the body of a compressor made in accordance with our present invention; Fig. 8 is a vertical cross section through a solenoid valve of a type found suitable to form a portion of the control system for the present invention; Fig. 9 is an end elevation of the lower portion of the solenoid valve detailed in Fig. 8; Fig. 10 is an enlarged partial section showing a portion of the control for the present invention including a master valve for controlling the number of pistons in operation and a master valve regulating and modulating device, the view being taken along line Ill-I of Fig. 7; Fig. 11 is a portion of a schematic representation of the electrical circuit required by our present invention; and Fig. 12 is the remainder of the wiring diagram, Fig. 12 being a continuation of Fig. 11,

Referring to Fig. 1 there is shown a vehicle body I0 mounted upon wheels I i, one of the pairs of which is provided with an axle I2 upon which is mounted a gear housing I3 enclosing gears deriving motion from the car axle, which drive a flexible, extensible shaft M. A suitable type of gear drive is set forth in the patent to Spicer, No. 2,026,076, dated Dec. 31, 1935, although other types of driving means including belt drives, several of which are well known, may be substituted therefor. The shaft l4 extends through a centrifugal clutch l of any well known type, the

application of Charles R. 'Neeson.

the car adjacent the ceiling thereof driven member of which is connected to the armature of a variable speed, shunt machine l6 which may act as a motor or as a generator, several makes of which are obtainable in the open market. The opposite end of the armature of the shunt machine I6 carries a pulley H which drives belts l8 passing about a pulley |6 mounted upon a multiple-cylinder, radial compressor of the type set forth in the aforementioned co-pending Refrigerant compressed by the compressor 20 passes through pipe 2| into a heat exchanger 22 through which cooling air is blown or drawn by fans 23, the heat exchanger thereby constituting an air cooled con denser. The compressed refrigerant is liquefied in the condenser and is accumulated in a receiver 24 from which the liquid passes through a liquid pipe 26 extending to the evaporator 26 located in the vehicle body. From the evaporator, in which expansion of the refrigerant causes cooling of air drawn therethrough, the refrigerant passes in ex.-

panded condition through a suction pipe 21 into the compressor 20 by which it is again forced through the refrigerating cycle.

A form of conditioning unit is illustrated in the drawings comprising a casing 30 mounted upon the floor of the car atone end thereof, preferably at one side of the closed vestibule, the casing being preferably enclosed within partitions to conceal the same and to confine the air treated by the 'unit. The unit may be mounted elsewhere such as in the ceiling area of the car or upon the floor in other parts of the car, the present disclosure being of 'a preferred embodiment in a preferred location. The unit may comprise a heating coil 3| inaddition to the evaporator coil 26 for the purpose of heating air in winter, and as is ordinary practice in railroad air conditioning, other conditioning means may be incorporated therein such as humidifying sprays. Condensed moisture extracted from the air may fall into a drain pan 32 'from which the moisture may be removed through an outlet 33 having a suitable connection thereto for the collection or waste of condensed moisture. I

A preferred manner of obtaining air for treatment and of distributing the same within the car after treatment is schematically indicated as follows: The bodies of most cars usually comprise double walls 34 and 35, at some suitable portion of which the outer wall is provided with louvres 36 through which outside air may be drawn. The inner wall has an opening adjacent the louvres and a filter 31 is suitably mounted adjacent the opening to remove soot and dust from the air drawn into the unit. The partition 46 which separates the unit from the remainder of the car interior is likewise provided with louvres 4| adiacent which a filter 42 may be placed in order to remove dust or other foreign matter from the air recirculated through the body of the car. The two streams of air which are admitted through filters 31 and 42 mix within thelower portion of the unit and the mixed air is drawn upwardly through the conditioning means by a suitable blower 43 driven by a motor 44 mounted upon the top of the unit. The discharge from the blower is conductedthrough a vertical duct 45 extending upwardly toward the overhead space within the car body and the air is -delivered therethrough into a central duct 46 running longitudinally of The duct 46 is provided with a series of openings 41 at suitable intervals for permitting the entrance of conditioned air into the passenger space. A suitable number of exhaust fans 60 may be provided adslll and to be discharged towards the side of the car since the development of high-speed trains has created the problem of combating so-called curtain air at the side of the car which might prevent suillcient air from being drawn through the compressor if the air movement were in the op posite direction, and also the high velocity air stream past the outside of the car aids in drawing air through the condenser from the comparatively quiet area near the center of the car.

, Fig. 7 illustrates in considerabie detail the form of compressor fully set forth and claimed in the aforementioned co-pending application. The compressor comprises a main casting 60 having a rear cover BI and a front cover 62 bolted thereto to form a hermetically sealed enclosure for the operating parts of the compressor. The crank shaft 63 (to which pulley I9 is attached) extends through the rear cover 6|, a shaft seal 64 being provided to prevent leakage between the crank shaft and the bearings therefor. The crank shaft is provided with a crank pin 65 from which ex tend radial piston rods 66 attached to pistons 61 operating in sleeve liners 68 extending through a suction manifold 69. A suction and discharge valve assembly 10 is provided for each piston, the same being held in place by a safety spring 1| and cylinder cap 12. Expanded refrigerant which is admitted through pipe 21 fills the interior of the crank case and the suction manifold 69, is admitted to the cylinder spaces, and is discharged in compressed condition through a series of discharge passages 15 leading to a disch manifold 16 extending circumferentially about the rear cover 6|. A discharge tube ll extends into an oil separator I8 provided with suitable baffles and screens which tend to accumulate any droplets of oil carried with the refrigerant, causing the same to drop to the bottom of the separator 18 and to be returned to the compressor through the medium of a valve 19 controlled by a float 80. The separated refriger- .which is returned to the interior of the crank shaft is removed from the crank case by a suitable scavenger pump 86 driven by gears 81 which rotate in unison with the crank shaft 63 and which also drive the force pump. The scavenger pump forces the lubricant through a pipe 88 into As-more clearly illustrated in Figs. 5 and 6,-we

' the crank case. I

I24 is pivoted to one end of a lever I26 mounted an oil tank 50 from which-it is drawn through the oil suction pipe 90 into the force pump and thence into thepassage 05. Further details of the compressor,'oil separator, lubricant system and allother parts associated therewith, may be ascertained-from the aforementioned application together with the co-pendlng applications of Charles R. Neeson, Serial Nos. 145,586 and 145,- 589, filed May 29, 1937.

As detailed in the aforesaid application, Serial No. 177,694, lubricant under pressure is admitted to a master unloader valve assembly 95 which is mounted upon the inner surface of the front cover 62. The lubricant is admitted to the valve througha pipe 96 connected to the passage 05 so that the interior of the valve may contain oil under pressure if the compressor is operating. The valve comprises a housing 91, through which tube 96 extends, and a'valve liner 98 having an opening 99 in communication with the tube 96, the opening admitting lubricant under pressure to an annular space I surrounding the stem of a plunger IOI having a closely fitting head I02 at one end, and a closely fitting head I03 at the other end. The oil is thus confined within the annular space I00 unless permitted to flow outward through slots in the liner 98, such as slot I04 which communicates with a tube I05 leading to an individual cylinder unloading mech anism exemplified by the piston I05 (Fig. 7) and piston rod I01. Further details of the individual cylinder unloadingmechanism may be ascertained from the aforesaid application, Serial No. 177,694, the same comprising means to hold the suction valve of the cylinder continuously in open position when urged to do so by oil under pressure whereby refrigerant admitted to the cylinder space is forced back into the suction manifold 69 without substantial compression thereof. Lubricant which may seep past the head I03 returns to the interior of the compressor through the open end of the liner 90. Lubricant which may tend to seep past the head I02 will be returned to the crank case through a bore IIO extending longitudinally of plunger IOI and an opening III in the side of the plunger.

There are five slots I04 illustrated, each of which communicates with a tube I05 leading to the unloading mechanism for an individual cylinder of a five-cylinder compressor as illustrated. As long as the compressor, and hence the force pump, is not operating there will be no pressure within the tubes I05 with the result that the springs II5 of the cylinder unloading mechanism will hold all of the suction valves in open position thereby unloading the entire compressor. If the compressor should start, the force pump will soon create suflicient pressure within space I00 and tubes I05 to cause all of the cylinder unloading means to become inoperative, thereby permitting the suction valves to operate in the normal fashion and the compressor to operate at full. capacity for the particular speed of rotation of the crank shaft.

The tubes I05 may be cut off from communication with the force pump by the master valve when moved by a master valve controlling mechanism I20 comprising a flexible metallic bellows I2I extending inwardly into the interior of the crank case and surrounding a guiding sleeve I22- which encloses a spring I23 compressed against a disc I24 fastened to the end of the bellows and thereby causing the same to hermetically seal A rod l25 fastened to the disc upon an arm I27 extending from the master causing head I02 successively to block or open the slots I04 leading to the tubes I05. The ball I28 is a check device for applying suflicient friction to cause the plunger to move in a series of steps thereby eliminating fluttering of the mechanism.

It is apparent that the interior of the crank case will exert a varying load upon the operating device comprising bellows I2I, which as seen in Fig. 10, has the fullest load exerted thereon causing the bellows to be compressed so as to bring disc I24 into engagement with the end of guiding sleeve I22. At this point the plunger is retracted to its fullest extent thereby causing all of the tubes to be in communication with the annular space I00. Thishigh pressure exists when the compressor is at rest with the result that the high and low sides of the refrigerating system have substantially balanced. If the compressor now starts, the force pump will likewise start and oil in all of the tubes I05 will soon be under sufiicient pressure to cause all of the individual cyl inder unloading means to be rendered inoperative, thereby causing the compressor to operate at full capacity. If the capacity at this speed is too great, the refrigerant within the crank case will be rarified to such an extent as to lower the interior pressure below the force exerted by spring I23 with the result that the master valve plunger is moved inward thereby preventing the exertion of pressure within certain of the tubes I05, with the result that the cylinders towhich such tubes extend become-unloaded. As the speed of the crank shaft increases, the number of cylinders necessary to maintain a given load decreases with the result that at very high car speeds one cylinder may be sufficient and even that one cylaxle is rotating fast enough to drive the com pressor faster than the speed imparted thereto by the motor, the number of cylinders required will be decreased so that in ordinary fast operation of modern trains only two or three cylinders will be in operation under maximum load conditions.

A feature of the present invention not found in the aforesaid application, Serial No. 177,694, is illustrated in Figs. 7, 8 and 9, and comprises a solenoid valve I30 inserted between the tube 96 and the passage 05 leading to the force pump which, when operated to close the oil line, will result in the entire unloading of the compressor due to the lack of suiiicient oil pressure to overcome any of the cylinder unloading means. There is thus provided a means of control which when operated will render the compressor entirely inoperative regardless of the speed of rotation of the crank shaft so that the compressor need not be disconnected from its driving means when no refrigeration is required, thereby eliminating master valve.

one of the clutches heretofore found necessary in railroadservice. The valve I comprises a,

solenoid I3I surrounding a needle valve plunger I40 and pipe I39 into the chamber I31. Some oil under pressure tends to leave chamber I31 and enter the passage I33 after flowing through passage I36, sieve I35 and passage I34 which, however, is prevented if the solenoid I3I is deenergized thereby causing plunger I32 to block the passage under the influence of gravity. If, however, the solenoid I3I is energized, the plunger I32 will be raised causing oil under pressure to fill a chamber I45 in which is situated a diaphragm I46 to which is attached a valve plunger I41. The oil under pressure moves the valve of plunger I41 downward, causing an enlargement I56 on the plunger I41 to be removed from the position shown in Fig. 9 to a lower position such as to permit communication between chamber E31 and delivery chamber I55 from which extends a pipe I52 connected to the tube 96 within the compressor which leads to the thereby removing pressure from the upper surface of diaphragm I46. A check valve I52 which is open as long as pressure exists within chamber I45, permits lubricant to flow through passage I53 into an exhaust chamber I54 provided with an opening I55 connected to a pipe I56 which drains the oil back into the compressor crank case. Oil which may be trapped beneath the head I50 is permitted to escape through a bypass I51 into the exhaust chamber I54 which also prevents the trapping of the plunger I41 in lowered position when urged to return to its upper position by a spring I58. Other types of valves are suitable for the purpose, but the foregoing type has'been found satisfactory. The solenoid valve comprises means to prevent the operation of the compressor whenever the solenoid is energized by suitable means subsequently described.

The foregoing mechanism serves to control the amount of refrigeration in accordance with the demand therefor as indicated by suitable means such as a thermostat located within the body of the car. If the thermostat in the car should indicate that cooling was desired, the compressor will deliver the proper amount of refrigerating medium to maintain a certain difference between the temperature of the air in the passenger'area and the temperature of the air immediately after the same has been treated by the cooling surfaces such as the evaporator coil 26. The master valve controlling bellows I2I serves to maintain this temperature differential since the temperature of the air within the passenger area is reflected in the superheat, and hence the pressure, of the expanded refrigerant entering the compressor. However, it is well known that in order to prevent shock to humans it is necessary to maintain a variable differential between inside and outside temperatures, in other words, the hotter the day, the higher the temperature should be within the passenger car in order to maintain a feeling of comfort and to prevent,

When the solenoid is again de'. energized, the plunger I32 closes opening l33 nervous shocks upon entering or leaving the car. Various systems have been devised to control this differential which operate upon the principle of varying the effective point of the controlling thermostat. We have devised a system whereby the variance is achieved by varyingthe eflective point of the master valve 35, which mechanism comprises the following: I

The bellows I2I is attached to cap piece I60 which is fastened to the cover plate 62 by means of bolts I6I, the cap piece serving to close an opening I62 through the cover plate 62. The guiding sleeve I22 is fastened to the side of an opening I63 extending through the cap piece I60 through which the spring I23 extends. The spring is compressed between the disk I24 at one end, and a movable pressure regulating plate I65 at the other end, which plate is located within a hood I66 fastened to the plate to form therewith an enclosure, and which is guided by a guide pin I61 attached to the inner surface of the hood I66. A guide rod I10 is fastened at its inner end to the pressure disc I24 and to the operating rod I25 and moves therewith, its outer end being guided in a loosely fitting bore I'II in the stem I12 of the pressure regulating member I65.' The spring I23 is so proportioned as to be overcome by high pressure existing within the crank case and to move the master valve plunger against the friction of ball I23 in definite increments of movement according to the suction pressure existing in the crank case during the operation of the compressor. The initial compression of the spring I23 is obviously controlled by the distance between the end of stem I12 and the end of guide sleeve I22. This initial compression may be small if the guide pin I61 bears against the inner end of its socket, or may be adjustably larger depending upon the separation of the pressure regulating plate I65 from the hood I66. The pressure regulating plate I65 is fastened to one end of a flexible bellows I15, the other end of which is fastened to an annular member I16 which is fastened to the inner surface of the hood I66, the hood, pressure regulating plate, bellows and annular member forming a hermetically sealed chamber I11. A charge of some thermally expansive fluid may be placed within the chamber I66, the quantity of the charge and its pressure determining the extent of separation of pressure regulating plate I65 and the hood I66; and,therefore, determining the initial compression of spring 523. An adjusting device may be supplied, the same comprising an auxiliary cylinder I18 in communication with the chamber I11 within which is mounted a plunger I19 which may be adjustably positioned by means of a thumb screw I80. Rotation of the thumb screw results in variations of the internal space within cylinder I18 and thereby results in variation of the pressure within chamber I11 which causesa variation in the initial compression of spring I23. Other means for adjusting the pressure of the fluid charge within chamber I11 may be utilized, several such means being set forth in the patent to Dube, No. 2,095,358, October 13, 1937.

As will be apparent from an inspection of "Figs. 2, 5 and 7, the hood I66 is located in the circuit extending from main line perature is very high it becomes increasingly easier for spring I23 to overcome the pressure of the refrigerant within the crank case, and the individual cylinder unloaders are caused to operate at increasingly higher pressures which means that less refrigerant will be supplied to the evaporator. By the proper adjustment of thumb screw I80, the action of the compressor can be so regulated as to maintain'a properly modulated temperature within the passenger area. It is to be noted that the cap piece I60 is spaced from the front cover 62 so as to be surrounded by air in motion and the cap piece I60 serves to prevent radiation from the compressor which might otherwise prevent accurate control by the modulating device.

Having described the mechanical features of our invention it is thought .best to describe a form of control" circuit which may be utilized to operate the same. Figs. 11 and 12 set forth in schematic fashion a complete control circuit, the details of which should be readily apparent to those skilled in the art. The circuit includes a battery I80 situated upon the vehicle from which extend main lines I8I and I82 to the shunt machine I6 which is provided with a motor-generator control comprising a generating field relay I83, motoring field relay I04, automatic starter I85, exciter I06 and other equipment. A line I90 extends from main line 82 to a blower fan contactor I9I which is operated by a solenoid I92 in series with a fan thermostat I93 and an emergency switch by means of which a circuit may be completed from line I90 to line I94 through the blower fan motor 44 and the exhaust fan motor 50, so that the blower fan and'exhaust fan may be operated under control of the fan thermostat I93 to ventilate the car when the temperature is above some predetermined temperature such as 65 F., or at any time through the manual switch. A line I95 extends from the main line I82 through a condenser fan contactor I96 to the condenser fans 23 and back to battery through line I8I so that whenever condenser fan contactor is closed, the condenser fan motors will be operated. The condenser fan contactor is closed by a solenoid IS! in a line I98 which includes switches, such as high and low pressure cutouts I99 for the compressor 20, a manually operatable switch 200 for controlling the compressor and a speed switch 20I, and which leads to the motoring and generating controls. When manual switch 200 is placed in the automatic position the circuit to the relay I 91 may be completed by a thermostatic element 202 which may make contact at some preselected temperature, usually about '72 to 82 degrees.

If the car is stationary, the speed switch 20I will be in the position shown in Fig. 11 which means that the motor field relay I84 will be energized and the shunt machine I6 will operate as a motor whenever the thermostat 202 completes the circuit through the condenser fan contactor, low voltage relay and motor field relay to the automatic starter. Speed switch 20I is a means responsive to the speed at which the vehicle is moving and may comprise a centrifugal weight mechanism 205 driven by a belt 206 (Fig. 5) deriving motion from the car axle. Whenever sufficient speed has been attained, the centrifugal weights 205 will'cause the switch 20I to open the I82 to the motoring field relay I84 and back to battery through main line I8I and to close the circuit extending from main line I82 to the generating field relay I83 and back to battery through main line I8I, so that at certain critical speeds of the vehicle the motoring action may cease and the generating action may commence to charge the battery.

We may cease motoring and commence generating at some preselected speed at which the speed of rotation of the car axle is sufiicient to rotate the armature fast enough to generate full load voltage. It is also within the range of the invention to have the motoring cease at one speed, such as two miles per hour, and to cause the generating field relay to be energized at another definite critical speed, such as 27 miles per hour. The latter mode of operation is preferable for several reasons; the primary reason being that the gear ratios of ordinary axle driving means are such as to cause the generator armature to rotate at such a speed that a car speed close to 27 miles per hour is necessary for the generation of full load voltage; the second reason being that the centrifugal clutch I5 would be better made if designed to engage at a speed such as 27 miles per hour rather than at a lower speed; and a third reason being that the motoring action of the machine may be stopped before clutch engagement so as not to clash with the mechanical drive in case the car starts to move in an opposite direction from the direction indicated by the direction of rotation of the armature when motoring. It is also within the range of our invention to have the motor cease operating at a low speed such as two miles per hour; to have the clutch I5 designed to engage at a higher speed, such as 10 miles per hour, so as to cause the compressor to operate through the mechanical means whenever the car is travelling at a speed equal to or above 10 miles per hour, and then to energize the generating field relay just prior to a car speed of 27 miles per hour which is necessary for the generation of full load voltage. The third mode of operation is preferred inasmuch as there are some railroad lines which operate their trains for some period of time at speeds between 5 and 20 miles per hour, in which event the cooling of air for the passengers comfort would continue as long as some charge remained in the battery for standby service, and as long as the car moves above the cutin speed of the clutch I5. Of course, the circuit may include a plug 2I0 placed in parallel with the battery I80 in order to drive the motor from a stationary source of current during standby operation in order not to excessively drain the battery.

It will be noticed that the thermostat 202 is in series with the low speed contacts of the speed switch 20I, and hence is in series with the motoring field relay so that the motor can only operate in case cooling is demanded within the vehicle. The high speed contacts of speed switch 20I are placed in line 206 which extends through generating field relay I83 back to battery, hence the generating action is not under control of the thermostat and whenever the armature is mechanically rotated by the car axle above the generating speed thereof the battery will be charged thereby.

A line 2 extends from the blower fan contactor and joins a line 2I2 extending to an interlock 2I3 between the motoring fieldrelay and the generating field relay so that current can be supplied to interlock 2 I 3 whenever and only when the blower fan contactor has been energized. If 1 motoring field relay is closed, a circuit will be completed to wire 2, interlock 2l3, wire 2l5, condenser fan contactor I56 and valve solenoid l3| back to battery, it the condenser fan contactor 196 has been operated by energizing solenoid I91. As previously explained, this results in the operation of the solenoid valve to control the flow of oil under pressure to the master valve 95, so that during standby operation the motoring drive for the compressor and the solenoid valve will be energized whenever the thermostat makes contact. The motoring drive and the solenoid valve will be de-energized, completely stopping the compressor, whenever the thermostat 2G2 breaks contact.

If the car is in motion and the compressor is operated by means of the axle drive, the condenser fan contactor may be energized through a circuit including the thermostat 202. Therefore, the condenser fan may operate, and due to the action of speed switch 2M, the generating field relay is energized and a circuit completed including wire 2i i, wire 2J2, interlock M3, generating iield relay i183, wire M5 and condenser fan contactor lSt through solenoid valve i239. The solenoid valve llll will again be energized to cause the master valve to control the action of the compressor. Whenever cooling is no longer necessary within the vehicle, the thermostat hi2 may brealr contact, thereby opening the condenser "fan contactor and closing the solenoid valve, and thereby causing the complete unloading of the compressor.

During the time the compressor is being operated, either at a variable speed by the me chanical drive or at a constant speed by the electrical drive as controlled by the thermostat illiil, the solenoid valve may be energized to perrnit oil under pressure to iiow to the unloader master valve. As long as pressure within the crank case is so high as to indicate the necessity for all cylinders being in operation, all will operate. However, as'the temperature of the air within the car drops, or the car gains speed, the

superheat and pressure of the gas within the crank case will drop, thereby causing the master valve successively to cut oil the oil pressure to the individual cylinder unloading means and successively decreasing the number of cylinders in operation until, conceivably, none of the cylinders will be effective. there is continued deor cooling as sensed by thermostat oellows the pressure within the cranlz will e. causing the loading of cylinders in succession (or perhaps the interrnittent loading and unloading or individual cylinder or cylinders). As soon as the thermostat Ztd indicates that the air within the vehicle is at a satisfactory temperature, the solenoid valve will be tie-energized, thereby stopping the oil pressure to the roaster valve and causing the complete unloading or the compressor regardless of the superheat and pressure of the gas within the crank case. When the compressor is unloaded there will be no gas compressed thereby and the pressure within the system will balance on both sides of the evaporator thereby causing the pressure within the crank case to rise. If thermostat 202 now closes thecompressor will operate through the motor when the car is standing still or moving at low speeds, or through the axle drive when the car is moving above. the cut-in speed of the clutch. If the car had been standing or if the clutchhad not been cut in previously the oil pump must operate for a short period of time in order to build up su cient amazes pressure to cause the compressor to operate under control of the master valve, but if the car had been moving above the cut-in speed of the clutch, the crank shaft of the compressor and the oil pump would have been rotating so that oil pressure would be immediately available to cause the master valve to control the operation of the compressor. As soon as oil pressure is available the compressor will be loaded and will henceforth operate under control of the solenoid valve and the master valve.

The differential regulating means comprising the chamber ill located in the stream of external air will change the effect of the master valve so that the pressure at which individual cylinders unload and the point of complete unloading willvary in direct response to variances of outside temperature regardless of the setting of thermostat 202. Thus it thermostat 202 is set to close at a temperature of 72 F. and the outside air is about 80 l t, the master valve may be so regulated as to cause complete unloading of the compressor when the air within the car is cooled to a temperature of 72 F; but if the outside air is at a temperature of 95 F. by way of example, the compressor may become completely unloaded when the inside temperature reaches 78 and, no further refrigeration will be accomplished even though the thermostat till? still remains in contact.

The thermostat tilt be a direct acting thermostat which will break contact at a definite setting, or it may be a differential thermostat, which as is well known with respect to such devices. may operate difierent points ing upon the load in the Thus it the outside temperature is very high, the thermo stat 262 may be oi the type which will have its operating point raised in accordance with a cer tain differential rating to he maintained between outside and inside temperatures. In either event the thermostat it]? is designed merely to as a low-limit safety device. The reason for this will he apparent in view of the statements of the preceding paragraph and the following ere planat'lon or the function of bellows till. it should be readily apparent to those skilled in the art that the back pressures and, hence, the suctlon pressure within the compressor, will vary accor g to the load w is mined by the amber outside terr number o; the

of occupants, the erature, relative humidity, the ots in use, the relative clearness i and other factors. The b-e' ov/s i528 and the associated mechanism are designed to operate at a range of baclc pressure oi, for example 3'? to lbs. per square inch, which means that when the pressure drops below 45 lbs. the first cylinder will be unloaded; the sec-- ond cylinder will be unloaded when the pressure is between 43 lbs. and ll lbs; and so on until the last cylinder is unloaded if the pressure drops below 37 lbs. per square inch. It is also equally obvious that with a. five-cylinder compressor and certain sizes of coils and blowers in operation a certain tonnage of refrigeration is performed. If the speed and load remain constant and one cylinder drops out of operation the tonnage performed will be reduced by twenty per cent. It the second cylinder is then unloaded the tonnage performed will be reduced by twenty-five per cent, the third cylinder will reduce the tonnage performed by thirty-three and one-third per cent, and so on. Each cylinder probably will not remain-unloaded constantly even at a constant 1111 the car, which load [f till till

speed with a constant load on the car since reductions in such percentages probably will reduce the capacity of the compressor below that necessary so that the performance chart of the compressor will undoubtedly present a series of rising and falling inclines, the average heights of which would follow substantially along a line representing the desired temperature conditions within the car as affected by the load. It may happen that during the course of this performance the compressor would tend to continue operation because of a temporary high pressure within the crank case whereas the air within the car would then be at the desired condition, in which case the thermostat would act as a lowlimit safety device to stop the action of the compressor regardless of the back pressure condition. The bellows therefor acts as a modulating-control as distinguished from a system comprising a non-variable compressor which starts and stops at the command of a thermostat and therefore, performs with much larger variances from the desired condition.

The performance of the compressor is not only affected by the operation of the low-limit thermostat 202 and the modulating action of the bellows I20, butwill also be affected by the action of the outside temperature differentiating control means comprising the chamber I11, which may so act as to raise the range of action of bellows I to limits such as 39 to 4'7 lbs., or to lower the same to limits such as 35 to 43 lbs. The foregoing will serve to show that the present invention comprises means to regulate the temperature within the car including a low-limit control thermostat, a back-pressure, responsive device acting as a modulating control, and differential control means to regulate the back-pressure responsive device.

Having described a preferred embodiment of our invention, it should be readily apparent to those skilled in the art that modifications in arrangement and detail thereofmay be madewithout departing from the spirit of the invention as expressed in the following claims.

We claim:

1. In a vehicle refrigerating system a variable capacity refrigerant compressor located on the vehicle and-cooling means located within the vehicle for lowering the temperature therein, electrical driving means for said compressor including a motor mechanically connected thereto, mechanical driving means deriving energy from the motion of the vehicle for driving said compressor at a variable speed, means associated with said compressor for partially unloading the same in response to the suction pressure of the refrigerant, means for selecting one or the other driving means for the compressor, means responsive to the temperature within the vehicle for controlling the operation of the compressor by starting and stopping said motor when the selecting means has selected the electrical driving means,

and means for controlling the operation of the compressor by completely unloading or permitting the variable loading of the compressor when the selecting means has selected the mechanical driving means.

2. In a railroad car refrigerating system a variable capacity refrigerant compressor located on the car and cooling means located within the car for lowering the temperature therein, electrical drivi'ng means for said compressor including a motor mechanically connected thereto-and power generating and storing equipment having electrical connection to said motor, mechanical driving means for driving said compressor at a variable speed, means associated with said compressor for partially unloading the same in response to the suction pressure of the refrigerant, selecting means for selecting one or the other driving means for the compressor, means responsive to the temperature within the car for controlling the operation of the compressor by starting and stopping said motor when the selecting means has selected the electrical driving means, and means for controlling the operation of the compressor by completely unloading or permitting the variable loading of the compressor when the selecting means has selected the mechanical driving means.

3. In a railroad car refrigerating system a variable capacity refrigerant compressor located beneath the car and cooling means located with in the car for lowering thetemperature therein, electrical driving means for said compressor including a motor mechanically connected thereto and power generating and storing equipment having electrical connection to said motor, mechanical driving means deriving energy from the motion of the car for driving said compressor at a variable speed directly corresponding to the speed of the car, means associated with said compressor for partially unloading the same in response to the suction pressure of the refrigerant, speed-responsive means for selecting one or the other driving mean for the compressor, means responsive to the temperature within the car for controlling the operation of the compressor by starting and stopping said motor when the speedresponsive means has selected the electrical driving means, and means for controlling the operation of the compressor by completely unloading or permitting the variable loading of the compressor when the speed-responsive means has selected the mechanical driving means.

4. In the cooling of vehicles the combination with a vehicle of a refrigerant compressor operated at a variable speed in accordance with the speed of the vehicle, said compressor including a plurality of cylinders and means successively to unload individual cylinders in response to the suction pressure of the refrigerant, means to prevent the compression of refrigerant by any of said cylinders, and a thermostatic device for operating said last-mentioned means in response to the temperature within the vehicle.

5. In a. cooling of railroad cars the combination with a car of a refrigerant compressor operated at a speed varying with the speed of movement of the car, said compressor including a plurality of cylinders and means successively to unload cylinders in response to the suction pressure of the refrigerant, means to prevent the ccmpression of refrigerant by any of said cylinders, and a thermostatic device for operating said last-mentioned means in response to the temperature within the car.

6. In the cooling of railroad cars the combination with the car of a refrigerant compressor operated by movement of the car, said compressor comprising a crank shaft having mechanical connection to an axle of the car so as to be driven,

at a variable speed varying in proportion to the speed of the car, and including a plurality of cylinders and means successively to unload individual cylinders in response to the refrigerant pressure within the compressor, means to prevent the compression of refrigerant by any of said cylinders, and a thermostatic device for operating said last-mentioned means in response to the temperature within the car.

7i In the cooling of railroad cars the combination with the car of a refrigerant compressor comprising a plurality of cylinders, means successively to unload individual cylinders in response to the suction pressure of the refrigerant, and means to regulate the action of said unloading means in response to the temperature outside of the car.

8. In the cooling of vehicles the combination with a vehicle of a refrigerant compressor comprising a plurality of cylinders, means successively to unload individual cylinders in response to the suction pressure of the refrigerant, means responsive to the temperature Within the vehicle to prevent the compression of refrigerant by any of said cylinders and means to regulate the action of said individual cylinder unloading means in response to the temperature outside of the vehicle.

9. In a refrigerating system, a refrigerant compressor comprising a plurality of cylinders, means successively to unload individual cylinders in respouse to the suction pressure oi the refrigerant being compressed thereby, and means to regulate the action of said unloading means in response to the temperature of the air surrounding said cornpressor.

10. In a refrigerating system ior an enclosure a refrigerant compressor comprising a plurality of cylinders, means successively to unload individual cylinders in response to the suction pressure of the refrigerant, and means to regulate the action or" said unloading means in response to the temperature existing outside or the enclosure loerefrigerated.

iii. In a railroad car refrigerating system a var lalole capacity refrigerant compressor located on the car and cooling means located within the car for lowering the temperature therein, electrical driving means for driving said compressor including a motor-generator having an armature incchanically connected thereto and power storing equipment deriving a charge from said generator and having electrical connection to said motor,

mechanical driving means for driving said compressor at a variable speed in accordance with the speed of the car, said mechanical n cans comprising a shaft deriving motion from a part oi the car, said armature, and a speed-responsive clutch and armature,

tially unloading the me response to the suc tion pressure of relrige ant, selecting means associated the compressor, said selecting means including said clutch and speed-responsive means ior selecting either the motoring or the generating function of said motor generator at critical speeds of the car, means responsive to the temperature within the car for controlling the operation of the compressor by starting and stopping the motoring function of, said motor-generator when the selecting means has selected the electrical driving means, and means for controlling the operation of the compressor by completely unloading or permitting the variable loading of the compressor when the selecting means has selected the mechanical driving means. I

12. In a railroad car refrigerating system a variable capacity refrigerant compressor located on the car and cooling means located within the car for lowering the temperature therein, electrical driving means for driving said compressor including a motor-generator having an armature mechanically connected thereto and power storing equipment deriving a charge from said generator and having electrical connection to said motor, mechanical driving means for driving said compressor at a variable speed in accordance with the speed of the car, said mechanical means comprising a shaft deriving motion from a part of the car, said armature, and a speed-response clutch interposed between said shaft and said armature, means associated with said compressor for partially unloading the same in response to the suction pressure of the refrigerant, selecting means for selecting one or the other driving means for the compressor, said selecting means including said clutch and speed-responsive means for selecting either the motoring or the generating function of said motor-generator at critical speeds of the car, means responsive to the temperature within the car for controlling the opena'tionof the compressor by starting and stopping the, motoring function of said motor-generator when the selecting means has selected the electrical driving means, means for controlling the operation of the compressor by completely unloading or permitting the variable loading of the compressor when the selecting means has selected the mechanical. driving means, and means for regulating the action of said partial unloading means in response to the temperature outside of the car.

deriving energy from the motion of the vehicle and driving said compressor at a variable speed, means for selecting one or the other driving means for compressor, and means to vary the capacity of the compressor in accordance with the load thereon and the speed of operation thereof.

l air conditioning mechanism for a pas-- 1' vehicle, a cooling comprising coma "ace cooler for "resting the air,

' (an to control system comprising it thermostat to: stopping said compressor when e inside air reaches W l or limit of ternperature, a modulating control for said compressor comprising means to vary the capacity thereof in response to the back pressure oi the system, and a differential regulating device for altering the action of said modulating control in response to outside temperatures.

15. In air conditioning mechanism for an enclosure, a cooling system comprising a compressor and a surface cooler for treating the air, and means to control said system comprising a modulating control for said compressor comprising means to vary the capacity thereof in response to the back pressure of the system, and a differential regulating device for altering the action of saidmodulatlng control in response to outside temperatures,

Iii-3 till 

